Experiences with a modified Giovannetti diet with about 18 g of protein containing the daily minimum requirement of essential amino acids are described in 26 patients with chronic renal failure who took the diet for up to 8 months. The clinical and biochemical response to the diet is described. In the presence of G.F.R. of less than 2 ml/min there was an amelioration in gastro-intestinal symptoms ; all uraemic symptoms were relieved in patients with a G.F.R. of 3 ml/min or more. Anaemia improved spontaneously in the majority of patients. Comfortable life was prolonged by the diet for several months; when fatal renal failure finally supervened the clinical picture differed from that seen in terminal uraemia on a normal diet. Gastro-intestinal symptoms and pericarditis were absent, but hyperkalaemia, severe acidosis, bleeding and agitation developed in the ambulant patient, and were signs of impending death. The term ‘modified terminal renal failure syndrome’ is used to describe this changed picture of extreme renal failure in patients on the diet.